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  <div id="layout-content"><div id="function.lcg-value" class="refentry">
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  <h1 class="refname">lcg_value</h1>
   <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">lcg_value</span> &mdash; <span class="dc-title">组合线性同余发生器</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.lcg-value-description">
  <h3 class="title">说明</h3>
   <div class="methodsynopsis dc-description">
    <span class="methodname"><strong>lcg_value</strong></span>(): <span class="type">float</span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>lcg_value()</strong></span> 返回范围为
   (0, 1) 的一个伪随机数。本函数组合了周期为
   2^31 - 85 和 2^31 - 249 的两个同余发生器。本函数的周期等于这两个素数的乘积。
  </p>
  <div class="caution"><strong class="caution">警告</strong>
 <p class="para">
  本函数并不会生成安全加密的值，并且<em class="emphasis">不可</em>用于加密或者要求返回值不可猜测的目的。
 </p>
 <p class="para">
  如果需要加密安全随机，则可以将 <span class="classname"><a href="class.random-engine-secure.html" class="classname">Random\Engine\Secure</a></span> 引擎用于
  <span class="classname"><a href="class.random-randomizer.html" class="classname">Random\Randomizer</a></span>。对于简单的用例，<span class="function"><a href="function.random-int.html" class="function">random_int()</a></span>
  和 <span class="function"><a href="function.random-bytes.html" class="function">random_bytes()</a></span> 函数提供了操作系统的 <abbr title="Cryptographically Secure PseudoRandom Number Generator">CSPRNG</abbr> 支持的方便且安全的 <abbr title="Application Programming Interface">API</abbr>。
 </p>
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 <div class="refsect1 parameters" id="refsect1-function.lcg-value-parameters">
  <h3 class="title">参数</h3>
  <p class="para">此函数没有参数。</p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.lcg-value-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   介于 0.0 和 1.0（含）之间的伪随机浮点值。
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.lcg-value-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.rand.html" class="function" rel="rdfs-seeAlso">rand()</a> - 产生一个随机整数</span></li>
    <li class="member"><span class="function"><a href="function.mt-rand.html" class="function" rel="rdfs-seeAlso">mt_rand()</a> - 通过梅森旋转（Mersenne Twister）随机数生成器生成随机值</span></li>
   </ul>
  </p>
 </div>

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